It's tempting to think of Verizon and Comcast as the only players if those are the only ones you can think of.
Firstly, most people do not chose between those two, and in certain locations - more all the time - there are more than two choices. For example, Philadelphia is developing its idea of providing 1MB wi-fi to everyone in the city limits. Their partner: Earthlink.
Comcast wasn't a player at all ten years ago, and Verizon was only a baby bell 10 years ago. Today Comcast is hardly a player, capable of providing VOIP to only
16 million homes. You can bet that, in ten years, the rules will have changed completely once again. And if broadband players can automatically get an extra $30 out of providing a clear 30k or so (all that's required to devote to voice) of their 1Meg to devote to voice, there are going to be a lot more broadband players.
More and more people have the capability to reach their office via VPN and include voice over that connection. Are the providers going to mess with those packets? Think those people won't figure it out?
Can nobody call customer service when they have a problem? Will Comcast lie when people ask why they can't get Skype? What will Skype customer service say?